Unit Testing Guidelines

Guidelines

In general, all functional code should be tested with unit tests. All unit tests should comply with the following requirements:

1. Unit tests should use the pytest module.

2. The tests that cover a module called pyreal/path/to/a_module.py should be implemented in a separated module called tests/pyreal/path/to/test_a_module.py. Note that the module name has the test_ prefix and is located in a path similar to the one of the tested module, just inside the tests folder.

3. Each method of the tested module should have at least one associated test method, and each test method should cover only one use case or scenario.

4. Test case methods should start with the test_ prefix and have descriptive names that indicate which scenario they cover. Names such as test_some_methed_input_none, test_some_method_value_error or test_some_method_timeout are right, but names like test_some_method_1, some_method or test_error are not.

5. Each test should validate only what the code of the method being tested does, and not cover the behavior of any third party package or tool being used, which is assumed to work properly as far as it is being passed the right values.

6. Any third party tool that may have any kind of random behavior, such as some Machine Learning models, databases or Web APIs, can be mocked using the mock library, and the only thing that will be tested is that our code passes the right values to them.

7. Unit tests should not use anything from outside the test and the code being tested. This includes not reading or writing to any file system or database, which will be properly mocked.